The present invention relates to a valve for use in an inhalator for aerosolizing a fluid stored in a container by using high pressure gas, for example, liquefied carbon dioxide (CO2) gas, as propellants, and more particularly to an improved valve adapted for restraining excessive increase in pressure within the container.
There is known apparatus adapted for aerosolizing a fluid such as medicine, that is stored in a container along with high pressure gas as propellant, through a valve fixed to an inlet of the container. The apparatus of this type has conventionally utilized a specific fluorocarbon (flon) as propellant. At present, the apparatus tends to use hydrofluorocarbon HFC134a as an alternative of the specific flon with increasing concern about environmental protection. However, HFC134a influences not ozonosphere but global warming not less than one thousand times the degree caused by CO2. Thus, if HFC134a is used with great frequency, it seems that serious environmental problem occurs. Accordingly, use of CO2 gas or inert gases, for instance, nitrogen, helium, neon, krypton, xenon and radon, acting as aerosol propellant, is at present proposed.
In the case of using such gases as propellant, it is required to liquefy or compress the gases for reducing a size of container as well as the flon conventionally used. The liquefied gases have a high vapor pressure. For example, liquefied CO2 gas has vapor pressure of 60 kgf/cm2 at 20xc2x0 C. It is also desirable that inert gases are liquefied or compressed under pressure of not less than 50kgf/cm2 in order to increase volumetric efficiency thereof. Japanese Patent Application First Publication No. 7-241498 discloses an aerosol using such liquefied gas.
The liquefied gas as propellant to be filled in the container has high vapor pressure as described above. The vapor pressure within the container tends to rapidly increase in response to even slight temperature rise of the ambient atmosphere. Therefore, such the aerosol must be handled with considerable care.
The above-described conventional art discloses the aerosol including a gas cartridge, a sealing plate fixed to an opening of the gas cartridge, and a gas-emitting valve mounted to the opening of the gas cartridge. Upon using the aerosol, the sealing plate is pierced by a needle connected with the valve to permit liquefied gas to be discharged from the gas cartridge through the sealing plate pierced. The sealing plate is adapted to be locally ruptured and escape the liquefied gas from the gas cartridge in response to increase in vapor pressure therewithin during storage before use. The conventional art has effects of avoiding contingencies that may be caused due to the increasing vapor pressure within the gas cartridge, whereby the gas cartridge can be safely stored. However, if the gas cartridge is used once and then vapor pressure therewithin excessively increases, the conventional art can no longer teach any effective measure.
It is an object of the present invention to provide a valve for use in an inhalator that is capable of relieving pressure within a container of the inhalator in response to a large increase in vapor pressure therewithin.
It is a further object of the present invention to provide an inhalator for aerosolizing fluid stored in a container with pressurized gas, that is capable of always restraining excessive increase in vapor pressure within the container.
According to one aspect of the present invention, there is provided a valve for an inhalator including a container having a pressurized fluid, comprising:
a valve case secured to the container;
a valve pin moveable relative to said valve case, said valve pin cooperating with said valve case to define a fluid path for discharging the pressurized fluid from the container, said valve pin having a portion extending through said valve case into the container to be exposed to the pressurized fluid;
a seal arranged within said valve case so as to separate said fluid path into an upstream portion communicating with inside of the container and a downstream portion communicating with outside of the container; and
said valve pin defining a main passage always communicating with outside of the container and a bypass passage, said valve pin having a first position where fluid communication between said main passage and said upstream portion of said fluid path is blocked to prevent the pressurized fluid from being discharged from the container and a second position where fluid communication between said upstream portion and said downstream portion of said fluid path is established through said bypass passage to permit the pressurized fluid to flow from the container;
a valve pin adjuster shifting said valve pin between said first position and said second position in response to change in pressure acting on said valve pin, said valve pin adjuster being mounted to said valve pin.
According to a further aspect of the present invention, there is provided an inhalator, comprising:
a container having an open end and a pressurized fluid;
a valve case secured to the open end of said container;
a valve pin moveable relative to said valve case, said valve pin cooperating with said valve case to define a fluid path through which said pressurized fluid is discharged from said container, said valve pin having a portion extending through said valve case into said container to be exposed to said pressurized fluid;
a seal arranged within said valve case so as to separate said fluid path into an upstream portion communicating with inside of said container and a downstream portion communicating with outside of said container; and
said valve pin defining a main passage always communicating with outside of said container and a bypass passage, said valve pin having a first position where fluid communication between said main passage and said upstream portion of said fluid path is blocked to prevent said pressurized fluid from being discharged from said container and a second position where fluid communication between said upstream portion and said downstream portion of said fluid path is established through said bypass passage to permit said pressurized fluid to flow from said container;
a valve pin adjuster shifting said valve pin between said first position and said second position in response to change in pressure within said container, said valve pin adjuster being mounted to said valve pin.
According to a still further aspect of the present invention, there is provided a valve for an inhalator including a container, comprising:
a pressurized fluid stored in the container;
a valve case secured to the container;
a valve pin moveable relative to said valve case, said valve pin cooperating with said valve case to define a fluid path through which said pressurized fluid is discharged from the container, said valve pin having a portion extending through said valve case into the container to be exposed to said pressurized fluid;
a seal arranged within said valve case so as to separate said fluid path into an upstream portion communicating with inside of the container and a downstream portion communicating with outside of the container; and
said valve pin defining a main passage always communicating with outside of the container and a bypass passage, said valve pin having a first position where fluid communication between said main passage and said upstream portion of said fluid path is blocked to prevent said pressurized fluid from being discharged from the container and a second position where fluid communication between said upstream portion and said downstream portion of said fluid path is established through said bypass passage to permit said pressurized fluid to flow from the container;
a valve pin adjuster shifting said valve pin between said first position and said second position in response to change in pressure acting on said valve pin, said valve pin adjuster being mounted to said valve pin.
According to a further aspect of the present invention, there is provided an inhalator, comprising:
a container having an open end;
a pressurized fluid stored in said container;
a valve case secured to the open end of said container;
a valve pin moveable relative to said valve case, said valve pin cooperating with said valve case to define a fluid path through which said pressurized fluid is discharged from said container;
a seal arranged within said valve case so as to separate said fluid path into an upstream portion communicating with inside of said container and a downstream portion communicating with outside of said container; and
said valve pin defining a main passage always communicating with outside of said container and a bypass passage, said valve pin having a first position where fluid communication between said main passage and said upstream portion of said fluid path is blocked to prevent said pressurized fluid from being discharged from said container and a second position where fluid communication between said upstream portion and said downstream portion of said fluid path is established through said bypass passage to permit said pressurized fluid to flow from said container;
a valve pin adjuster shifting said valve pin between said first position and said second position in response to change in pressure within said container, said valve pin adjuster being mounted to said valve pin.